Dermal image information processing device, dermal image information processing method, and program

ABSTRACT

A dermal image information processing device including a memory; and a hardware component that reads data from the memory and is configured to: acquire dermal image information showing ridge lines in a papillary layer; detect an singular region in a pattern of the ridge lines; detect a position that is furthest away from the singular region; determine a region for collation based on the detected position; and perform collation of the pattern of the ridge lines using only feature points that are included in the region for collation.

CROSS-REFERENCE TO RELATED APPLICATIONS

This is a Continuation Application of U.S. application Ser. No.15/736,146 filed on Dec. 13, 2017, which is a National Stage ofInternational Application No. PCT/JP2016/067791 filed Jun. 15, 2016, andwhich claims priority based on Japanese Patent Application No.2015-120660 filed on Jun. 15, 2015, the contents of all of which areincorporated herein by reference in their entirety.

TECHNICAL FIELD

The present invention relates to a dermal image information processingdevice, a dermal image information processing method, and a program.

BACKGROUND ART

In recent years, biometric authentication has attracted attention as oneof the authentication methods for identifying individuals. A biometricpattern such as a fingerprint has a feature that it does not change evenafter years of time, and is highly reliable for authentication.Meanwhile, still there is a possibility of unauthorized acts using falsebiometric patterns such as false fingers, and techniques for preventingsuch unauthorized acts have also been developed.

For example, the technique disclosed in Patent Document 1 is a techniquefor determining a false finger with a transparent thin film attached onthe surface of a finger. Patent Document 1 discloses a technique ofclassifying an image region into a plurality of regions including atleast a skin region and a background region by using colors of pixelsincluded in a captured image, and using a characteristic of a regionthat is not classified either as the skin region or as the backgroundregion, to thereby determine whether or not a foreign object is presentaround a finger. According to this technique of Patent Document 1, aforeign object around a finger (a portion having a biological pattern)can be detected.

PRIOR ART DOCUMENTS Patent Documents

[Patent Document 1] PCT International Publication No. WO 2011/058836

SUMMARY OF INVENTION Problem to be Solved by the Invention

In the case of using a fingerprint as information for identifying anindividual, if the state of the skin of the finger is not good, there isa possibility that the same person is judged as another person. Forexample, in the case where the fingerprint is unclear due to roughness,wrinkles due to aging and the like, or burns, the accuracy offingerprint identity determination and the accuracy of abnormalitydetection are reduced, and there is a possibility that the same personis judged as another person.

An exemplary object of the present invention is to provide a dermalimage information processing device, a dermal image informationprocessing method, and a program, that are capable of solving the aboveproblems.

Means for Solving the Problem

A dermal image information processing device according to a firstexemplary aspect of the present invention includes: a dermal imageinformation acquisition unit that acquires image information indicatingan image of a papillary layer; and a singular region detection unit thatdetects a singular region indicating damage of the papillary layer,based on the acquired image information.

A dermal image information processing method according to a secondexemplary aspect of the present invention includes: acquiring imageinformation indicating an image of a papillary layer, and detecting asingular region indicating damage of the papillary layer, based on theacquired image information.

A program according to a third exemplary aspect of the present inventioncauses a computer to execute: acquiring image information indicating animage of a papillary layer, and detecting a singular region indicatingdamage of the papillary layer, based on the acquired image information.

Effect of the Invention

According to the present invention, even when the state of the skin isnot good, it is possible to reduce the possibility that the same personis erroneously judged as another person.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a schematic block diagram showing a functional configurationof an image information processing system according to a first exemplaryembodiment.

FIG. 2 is a block diagram showing a schematic functional configurationinside a singular region detection unit in the first exemplaryembodiment.

FIG. 3A is a diagram showing an example of an abnormal pattern in adermal fingerprint in the first exemplary embodiment.

FIG. 3B is a diagram showing an example of an abnormal pattern in adermal fingerprint in the first exemplary embodiment.

FIG. 3C is a diagram showing an example of an abnormal pattern in adermal fingerprint in the first exemplary embodiment.

FIG. 4A is a diagram showing an example of a dermal fingerprint imageincluding an abnormal dermal ridge line direction in the first exemplaryembodiment.

FIG. 4B is a diagram showing an example of a dermal fingerprint imageincluding an abnormal dermal ridge line direction in the first exemplaryembodiment.

FIG. 4C is a diagram showing an example of a dermal fingerprint imageincluding an abnormal dermal ridge line direction in the first exemplaryembodiment.

FIG. 5A is a conceptual diagram schematically showing templatescorresponding to abnormal dermal ridge line directional patterns in thefirst exemplary embodiment.

FIG. 5B is a conceptual diagram schematically showing templatescorresponding to abnormal dermal ridge line directional patterns in thefirst exemplary embodiment.

FIG. 5C is a conceptual diagram schematically showing templatescorresponding to abnormal dermal ridge line directional patterns in thefirst exemplary embodiment.

FIG. 6 is a view showing a conceptually illustrated example of a dermalfingerprint image including dermal ridge line breakage in the firstexemplary embodiment.

FIG. 7 is a view showing dermal ridge line direction image data obtainedfor the example of the dermal fingerprint image in FIG. 6, in the firstexemplary embodiment.

FIG. 8 is a view showing an image obtained as a result of performing adirection smoothing process on the dermal ridge line direction image inFIG. 7, in the first exemplary embodiment.

FIG. 9 is a diagram showing an example of a dermal fingerprint imagebefore clipping processing, in the first exemplary embodiment.

FIG. 10 is a view showing an example of a dermal fingerprint image aftercutting out the dermal fingerprint shown in FIG. 9, in the firstexemplary embodiment.

FIG. 11 is a schematic block diagram showing a functional configurationof an image information processing system according to a secondexemplary embodiment of the present invention.

FIG. 12 is a view showing an image before applying Z-type surgery, inthe second exemplary embodiment.

FIG. 13 is a view showing an image after performing Z-type surgery, inthe second exemplary embodiment.

FIG. 14 is a block diagram showing a schematic functional configurationinside a repair unit, in the second exemplary embodiment.

FIG. 15 is a schematic diagram for explaining a method of Z-typesurgical dermal fingerprint restoration, in the second exemplaryembodiment.

FIG. 16 is a block diagram showing a schematic functional configurationof a repair unit according to a modification of the second exemplaryembodiment.

FIG. 17 is a schematic block diagram showing a configuration of a dermalimage information processing device according to a third exemplaryembodiment of the present invention.

EMBODIMENTS FOR CARRYING OUT THE INVENTION

Hereinafter, exemplary embodiments of the present invention will bedescribed. However, the following exemplary embodiments do not limit theinvention according to claims. Moreover, not all combinations of thefeatures described in the exemplary embodiments are necessarilyessential to the solution provided by the invention.

First Exemplary Embodiment

FIG. 1 is a schematic block diagram showing a functional configurationof an image information processing system according to a first exemplaryembodiment of the present invention. As shown in FIG. 1, the imageinformation processing system 1 includes an OCT (optical coherencetomography) 2 and a dermal image information processing device 3. Thedermal image information processing device 3 includes a dermal imageinformation acquisition unit 11, a singular region detection resultacquisition unit 12, a singular region detection unit 61, apre-registered information storage unit 62, a collation unit 116, and aresult output unit 121.

The OCT 2 and the dermal image information processing device 3 may beintegrally configured. For example, the computer included in the OCT 2may execute the function of the dermal image information processingdevice 3.

The OCT 2 obtains mutual interference caused by the phase differencebetween light reflected by emitting the finger as the observation target(laser light), and reference light, as an image of the pattern of lightintensity. In the OCT 2, by appropriately changing the wavelength of thelight, not only information on the surface of the finger but alsoinformation on the pattern inside the living body, from the surface to acertain depth (a depth of about several hundreds of micrometers or 2000micrometers), can also be acquired. Particularly, the OCT 2 acquires theposition information of the papillary layer of the finger, and generatesthe image information (data indicating the image) of the papillarylayer. A general OCT can be used as the OCT 2.

Instead of the OCT 2, a device capable of obtaining an image of thepapillary layer with a device other than the OTC, for example, anultrasonic tomographic imaging device may be used.

The papillary layer is a layer located at the boundary with theepidermis of the dermis. Human skin is formed by overlapping ofepidermis and dermis. The epidermis is present on the surface side(outside), and the dermis is present on the far side (inside). Thepapillary layer exists at the portion where the epidermis and the dermisare in contact with each other. In the vicinity of this papillary layer,concaves and convexes are present on the dermis side. This convex partforms ridge lines. Sweat gland pores are aligned along the convex partof the ridge line. The ridge line pattern formed on the dermis side canalso be seen as it is on the epidermis side. This pattern is generallycalled a fingerprint. Even if the epidermis is temporarily damaged, aslong as the ridge line structure in the dermis is maintained, when theepidermis is regenerated, a pattern based on the ridge line structure ofthe original dermis side is reproduced also on the epidermis side. Theshape of the protuberance (convex part) of this papillary layer can beregarded as being the same as the (original) shape of the ridge line.

In the following, the protuberance forming the ridge line in thepapillary layer is referred to as a dermal ridge line. Also, the patternof the dermal ridge line is referred to as a dermal fingerprint.

The dermal image information acquisition unit 11 acquires imageinformation of the papillary layer generated by the OCT 2.

The singular region detection result acquisition unit 12 acquiresinformation on a singular region of the papillary layer detected basedon the image information acquired by the dermal image informationacquisition unit 11.

More specifically, the singular region detection result acquisition unit12 requests the detection of the singular region, by passing the imageinformation of the papillary layer passed from the dermal imageinformation acquisition unit 11 to the singular region detection unit61. Then, the singular region detection result acquisition unit 12receives the information on the singular region detection result basedon this request. A specific processing method for detecting the singularregion will be described later. The information on the detection resultreceived by the singular region detection result acquisition unit 12includes information on the presence or absence of a singular region inthe image information of the passed papillary layer, and when a singularregion exists, information on the location (coordinate etc.) thereof.

The singular region is a region in which a pattern unique to the dermalfingerprint (a pattern different from a normal pattern) exists due tofactors such as a part of the living body being damaged. Examples of thecause of living body damage causing a singular region to occur include adeep injury that reaches the dermis, such as cuts, burns, burn sores dueto chemicals (for example, strong acids), and the like.

A specific method for detecting the singular region will be describedlater.

The collation unit 116 performs collation processing between the dermalimage information in the region other than the singular region in thedermal image information acquired by the dermal image informationacquisition unit 11, and the pre-registered image informationpreliminarily registered in the pre-registered information storage unit62. The collation unit 116 acquires information on the presence orabsence of a singular region and information on the position (range) ofthe singular region from the singular region detection resultacquisition unit 12. When performing the above collation processing, thecollation unit 116 can make at least either one of a positionaldeviation allowance which represents a degree to which positionaldeviation is allowed, and a mismatch allowance which represents a degreeto which a mismatch is allowed, to be variable. When it is determinedthat there is a singular region based on the information acquired by thesingular region detection result acquisition unit 12, the collation unit116 may perform adjustment so as to change either or both of theallowances in a direction in which the allowance increases (that is, ina direction in which it is considered that the degree of matching isincreased even if there are some differences).

The collation process itself performed by the collation unit 116 can beperformed using existing techniques. An outline of the process ofcollating a dermal fingerprint is as follows. For the collationprocessing, the collation unit 116 extracts characteristics of the inputdermal fingerprint image. The characteristics include the dermal ridgeline directions of the dermal fingerprint, the statistical valuesrelating to the distribution of the direction of the dermal fingerprint,the manner of connection of dermal ridge lines, the number ofdirectional singular points of the dermal ridge line for each type (thedirectional singular points such as a true circular core, a semicircularcore, and delta which will be described later), the mutual positionalrelationship of the directional singular points, the orientation ofstraight lines connecting a plurality of directional singular points,and the angle formed by these straight lines. The collation unit 116determines whether or not the plurality of dermal fingerprint imagescome from the same fingerprint by evaluating the above-describedcharacteristics of the plurality of dermal fingerprint images (or maycompare with the fingerprint image) with the proximity and/or thedistance in the characteristic space. In one example, the collation unit116 compares the characteristics of the dermal fingerprint image (orfingerprint image) preliminarily registered in the database against thenewly input dermal fingerprint image, and determines whether or not bothimages match.

In this type of collation processing, the above-mentioned positionaldeviation allowance is for example a value that represents the degree towhich the error in the position of the characteristic point in thefingerprint image is allowed. In addition, the above-mentionedmismatching allowance is a value that indicates the degree to whichcharacteristic mismatching is still allowed while it is regarded asmatching, when the two fingerprint images to be compared do notcompletely match. For example, the mismatching allowance may berepresented by a distance that is appropriately defined in thecharacteristic space, or may be expressed by the degree of the weight ofthe penalty that is given according to the distance.

The result output unit 121 outputs the collation result of the collationunit 116. The result output unit 121 may display the collation result ona screen, or may transmit the collation result to another device.

The result output unit 121 may output information indicating thesingular region detected by the singular region detection unit 61, inaddition to or instead of the collation result of the collation unit116. Regarding the output of the information indicating the singularregion, the result output unit 121 may display the singular region on ascreen, or the information indicating the singular region may betransmitted to another device.

The singular region detection unit 61 performs a process of analyzingimage information of the papillary layer passed from the singular regiondetection result acquisition unit 12, and determines whether or not asingular region is included in the image of the papillary layer. Thesingular region detection unit 61 outputs information on the presence orabsence of a singular region as a determination result. Moreover, when asingular region is included in the image of the papillary layer, thesingular region detection unit 61 outputs information on the position(position information indicating the range of the region). Details ofthe determination processing by the singular region detection unit 61will be described later.

The pre-registered information storage unit 62 stores fingerprint imageinformation or papillary layer image information registeredpreliminarily as biological pattern information. The pre-registeredinformation storage unit 62 holds the biological pattern information(fingerprint image information or papillary layer image information) inassociation with identification information for identifying theindividual. Further, the pre-registered information storage unit 62 mayfurther hold the above identification information and personal attributeinformation in association with each other. Specific examples ofindividual attribute information include name, information on registeredresidence, and information on individual legal status. Thepre-registered information storage unit 62 uses, for example, a magnetichard disk device, a semiconductor memory, or the like as a means forstoring information.

[Regarding Method of Singular Region Detection Processing]

In the following, an internal configuration of the singular regiondetection unit 61 and a method of singular region detection processingwill be described.

FIG. 2 is a block diagram showing a schematic functional configurationinside the singular region detection unit 61. As shown in FIG. 2, thesingular region detection unit 61 includes a common function group, anabnormal pattern detection function, an abnormal dermal ridge linedirection detection function, a dermal ridge line breakage detectionfunction, and a cutout work detection function. The common functiongroup includes a dermal ridge line direction detection unit 70, a dermalridge line pitch detection unit 71, a dermal ridge line intensitydetection unit 72, and a directional singular point detection unit 73.The operation of the singular region detection unit 61 using thesefunctions will be described below.

The singular region detection unit 61 first receives data of a dermalfingerprint image from the singular region detection result acquisitionunit 12.

The singular region detection unit 61 analyzes the received dermalfingerprint image using functions included in the common function groupthereof. Specifically, the dermal ridge line direction detection unit 70detects a dermal ridge line direction in the dermal fingerprint image.The dermal ridge line pitch detection unit 71 detects a dermal ridgeline pitch in the dermal fingerprint image. The dermal ridge lineintensity detection unit 72 detects a dermal ridge line intensity in thedermal fingerprint image. The directional singular point detection unit73 detects a directional singular point (singular point) in the dermalfingerprint image. The singular region detection unit 61 may detect onlyany one of a dermal ridge line direction, a dermal ridge line pitch, adermal ridge line intensity, and a direction singularity, but not all ofthem. The process itself of detecting these dermal ridge line pitch,dermal ridge line intensity, and directional singular point from thedermal fingerprint image is similar to a feature extraction process in ageneral fingerprint authentication technique and can be performed usingexisting techniques.

A dermal ridge line direction is a direction in which the dermal ridgeline is oriented. A dermal ridge line pitch is a width of paralleldermal ridge lines (a distance from one dermal ridge line to anotherdermal ridge line that is parallel to or adjacent to that dermal ridgeline). A dermal ridge line intensity is a degree indicating thelikelihood of being a dermal ridge line as information obtained from animage. A directional singular point is a portion where a dermal ridgeline direction becomes discontinuous in a dermal fingerprint image.

The singular region detection unit 61 first extracts a dermal ridge linedirection, a dermal ridge line pitch, and a dermal ridge line intensityfrom the received dermal fingerprint image using Gabor filters.Specifically, the singular region detection unit 61 applies the Gaborfilters in which the direction and pitch are stepwise changed for eachpixel included in the dermal fingerprint image. The singular regiondetection unit 61 regards the direction and the pitch of the filter thatyields the highest absolute value among these applied Gabor filters asthe dermal ridge line direction and pitch at that pixel. In addition,the absolute value of the filter applied value at that time is extractedas the dermal ridge line intensity.

The singular region detection unit 61 detects a directional singularpoint in the dermal fingerprint image. At a directional singular pointthere exists a directional shape called a delta and a directional shapecalled a core. Of these, the core can be further classified into a truecircular core and a semicircular core. A true circular core is a corewhose dermal ridge line rotates 360 degrees around the directionalsingular point. A semicircular core is a core whose dermal ridge linerotates 180 degrees around the directional singular point. However thesemicircular core that is actually detected is not limited to rotationof exactly 180 degrees. As a method of detecting a directional singularpoint, the singular region detection unit 61 may use an existingtechnique. As an example, a method for detecting a directional singularpoint is also disclosed in the literature [Asker Michel Bazen,“Fingerprint identification: Feature Extraction, Matching, and DatabaseSearch”, Twente University Press, 2002]. For each finger, the singularregion detection unit 61 stores the number of each of the detected truecircular cores, semicircular cores, and deltas and the position(coordinates) of the directional singular point of each of these, forprocessing in a later step. The singular region detection unit 61detects the direction of the pattern at the directional singular point(for example, in the case of a semicircular core, whether the side onwhich the dermal ridge line is open is the upper side or the lower sideof the finger), and stores the information for processing in a laterstep.

In addition to the example of the existing technique mentioned above,the singular region detection unit 61 may use yet another method. Inorder to improve the accuracy, the singular region detection unit 61 mayalso use in combination another means for correcting extraction errorsin dermal ridge line direction and dermal ridge line pitch.

Next, the singular region detection unit 61 performs processing fordetecting four types of singular regions in the dermal fingerprintimage. The four types are (1) abnormal pattern, (2) abnormal dermalridge line direction, (3) dermal ridge line breakage, and (4) cutoutwork. The features of the dermal fingerprints having these four types ofabnormality and the detection methods thereof will be described below.

((1) Abnormal Pattern Detection)

The singular region detection unit 61 includes an abnormal patterndetection unit 74 as a function for detecting an abnormal pattern. Theabnormal pattern detection unit 74 detects an abnormal pattern based onthe number and positional relationship of the directional singularpoints (delta, semicircular core, perfect circle core) detected above.Normal dermal fingerprint images are classified into four types ofpatterns from the dermal ridge line direction patterns. The four typesare arch-shaped pattern, loop-shaped pattern, spiral-shaped pattern, andvariant-shaped pattern. For each of these patterns, the number andpositional relationship of the directional singular points are defined.

Specifically, in the arch-shaped pattern, the number of semicircularcores is 0 or 1, and the number of deltas is also 0. That is to say, thecurve of the dermal ridge line is smooth. In the loop-shaped pattern,the number of semicircular cores is 1, and the number of deltas is 1 orless. In the spiral-shaped pattern, either the number of circular coresis 1 and the number of deltas is 2 or less, or the number ofsemicircular cores is 2 and the number of deltas is 2 or less. In thevariant-shaped pattern, either the number of semicircular cores is 3 andthe number of deltas is 3 or less, or the number of circular cores is 1,the number of semicircular cores is 1, and the number of deltas is 3 orless. In the case of a normal dermal fingerprint image, the positionalrelationship of the directional singular point also has a predeterminedrestriction.

Normal dermal fingerprint images have the above patterns. The abnormalpattern detection unit 74 detects an abnormal pattern image that cannotappear in a normal dermal fingerprint image as an abnormal pattern.Specifically, the singular region detection unit 61 detects the dermalfingerprint image as an abnormal pattern when any one of the followingconditions (A) to (F) is satisfied.

Condition (A): When there are two or more circular cores

Condition (B): When there are four or more semicircular cores

Condition (C): When two or more semicircular cores are present and oneor more circular cores are also present

Condition (D): When there are four or more deltas

Condition (E): Delta is present above the core (on the side near thefingertip)

Condition (F): When there are two or more semicircular cores on theupper side

That is to say, the singular region detection unit 61 detects thedirectional singular point of the dermal ridge line included in thedermal fingerprint image, and detects a singular region based on thecondition of the number of each directional singular point type or thecondition of the positional relationship between the types of thedirectional singular points.

One of the reasons why these types of abnormal patterns are detected indermal fingerprints is a surgical treatment applied to the finger. Whendeforming the fingerprint intentionally by a surgical operation,surgical operations including operations on the dermis may be performed,since the fingerprints return to original due to the metabolism of theskin, merely by deforming the epidermis. When a surgical operation isperformed on the dermis in this manner, the abnormal pattern asdescribed above can be detected.

FIG. 3A to FIG. 3C show examples of abnormal patterns in dermalfingerprints. In FIG. 3A to FIG. 3C, the circled portions are circularcores. Also, the portions indicated by triangles are deltas. The exampleof the dermal fingerprint image shown in FIG. 3A has two circular coresand four deltas. That is to say, this dermal fingerprint image meets theabove conditions (A) and (D), and the abnormal pattern detection unit 74determines that it has an abnormal pattern. The example of the dermalfingerprint image shown in FIG. 3B has two circular cores and fourdeltas. Also, in the example of FIG. 3B, a delta exists above the twocircular cores. That is to say, this dermal fingerprint image meets theabove conditions (A), (D), and (E), and the abnormal pattern detectionunit 74 determines that it has an abnormal pattern. The example of thedermal fingerprint image shown in FIG. 3C has two circular cores. Thatis to say, this dermal fingerprint image meets the above condition (A),and the abnormal pattern detection unit 74 determines that it has anabnormal pattern.

If an abnormal pattern is detected, the abnormal pattern detection unit74 outputs the type of the abnormality (any of (A) to (F) above) and theposition and type of the directional singular point concerning theabnormality.

Further, if an abnormal pattern is not detected, the abnormal patterndetection unit 74 outputs information indicating that an abnormalpattern is not detected.

((2) Abnormal Dermal Ridge Line Direction Detection)

The singular region detection unit 61 detects an abnormal pattern in thedermal ridge line directions. There are several patterns also inabnormal dermal ridge line directions. Typical three types of patternsare called comb type direction pattern, ω type direction pattern, and Xtype direction pattern for convenience. In the present exemplaryembodiment, the singular region detection unit 61 detects three types ofabnormal dermal ridge line directions, namely the comb type directionpattern, the ω type direction pattern, and the X type direction pattern.There is a possibility that these types of abnormal dermal ridge linedirection patterns may be observed at a boundary portion of thetransplanted epidermis part if an epidermis and dermis transplantoperation or the like has been performed. These patterns cannot be seenin normal dermal fingerprint images.

FIG. 4A to FIG. 4C show examples of dermal fingerprint images includingabnormal dermal ridge line directions.

FIG. 4A is an example of a dermal fingerprint image having an abnormaldermal ridge line direction called a comb type direction pattern. Thiscomb type abnormal dermal ridge line direction is a dermal ridge linedirection pattern which is likely to occur near the boundary of thetransplanted epidermis when the epidermis and dermis is cut and removedwith a scalpel, and a surgical operation such as changing the positionand replacement is performed.

FIG. 4B is an example of a dermal fingerprint image having an abnormaldermal ridge line direction called a ω type direction pattern. This ωtype abnormal dermal ridge line direction is also a dermal ridge linedirection pattern which is likely to occur near the boundary of thetransplanted epidermis when the epidermis and dermis is cut and removedwith a scalpel, and a surgical operation such as changing the positionand replacement is performed. In addition, the ω type direction patternis a pattern which is likely to occur also when a deep cut reaching thedermis is made to the arch-shaped portion of the fingerprint with ablade or the like.

FIG. 4C is an example of a dermal fingerprint image having an abnormaldermal ridge line direction called an X type direction pattern. Thisabnormal dermal ridge line direction of the X type is a dermal ridgeline direction pattern which is likely to occur in the stitched portionwhen the skin is tightly stitched with a surgical thread or the like.

FIG. 5A to FIG. 5C are conceptual diagrams schematically showingtemplates corresponding to each of the abnormal dermal ridge linedirection patterns (comb type, w type, and X type).

FIG. 5A corresponds to the X type direction pattern in the dermalfingerprint image.

FIG. 5B corresponds to the ω type direction pattern in the dermalfingerprint image.

FIG. 5C corresponds to the comb type direction pattern in the dermalfingerprint image.

The singular region detection unit 61 includes a comb type directionpattern detection unit 75, an ω type direction pattern detection unit76, and an X type direction pattern detection unit 77 in correspondencewith the abnormal direction patterns described above. The singularregion detection unit 61 performs processing for detecting theseabnormal direction patterns by using information on the dermal ridgeline direction and information on the dermal ridge line intensityalready detected by the above method.

A processing method for detecting each of the abnormal directionpatterns will be described below.

The comb type direction pattern detection unit 75 calculates and outputsthe degree indicating the likelihood of the comb type direction patternof the dermal fingerprint image using the data input of the dermal ridgeline direction and the dermal ridge line intensity preliminarilydetected based on the given dermal fingerprint image.

Specifically, the comb type direction pattern detection unit 75preliminarily holds comb type template data representing the directionpattern as shown in FIG. 5C in the internal memory. The comb typetemplate data is data obtained on the basis of a dermal fingerprintimage having the comb type direction pattern, and is stored in a twodimensional array corresponding to polar coordinates. “i” which is thefirst index of comb template data Tk (i, j) which is a two dimensionalarray, corresponds to the displacement angle around the center of thetemplate data. In this definition “i=1, 2, . . . , M”. This “i” is anindex value corresponding to each direction when 360 degrees in alldirections from the center of the dermal fingerprint image are cut inincrements of (360/M) degrees. Where the positive direction of thex-axis of the xy orthogonal coordinate system is 0 degrees, thecounterclockwise direction is the positive direction of the displacementangle. Moreover, a second index “j” corresponds to the distance from thecenter of the dermal fingerprint image. In this definition “j=1, 2, . .. , N”. This “j” is an index value corresponding to the distance fromthe center of the template. The value of each element of Tk (i, j) is atwo dimensional vector (unit vector) value representing the dermal ridgeline direction in the portion (small region) represented by this polarcoordinate.

The comb type direction pattern detection unit 75 calculates the maximumvalue of the sum of the inner products of the template direction Tk (k,t) and the direction vectors in the dermal ridge line direction withinthe circle of the image while changing the template rotation angle “t”,with respect to an arbitrary pixel position (x, y) in the given dermalfingerprint image. The maximum value is expressed by Ek (x, y) accordingto the following equation.

$\begin{matrix}{{{Ek}\left( {x,y} \right)} = {\max\limits_{{t = 1},\ldots \mspace{14mu},M}\left\{ {\sum\limits_{i = 1}^{N}\frac{{{Tk}\left( {t,i} \right)} \cdot {{Id}\left( {{x + {{dx}(i)}},{y + {{dy}(i)}}} \right)}}{N}} \right\}}} & \left\lbrack {{Equation}\mspace{14mu} 1} \right\rbrack\end{matrix}$

In Equation (1) above, Id (x, y) is a unit vector representing thedermal ridge line direction at a coordinates (x, y) of the dermalfingerprint image. Tk (t, i) is the i-th direction of the comb template(rotation angle is t). dx (i) is the x coordinate displacement of thei-th element in the template. dy (i) is the y coordinate displacement ofthe i-th element in the template.

That is to say, the value of Ek (x, y) calculated by this Equation (1)is a correlation value when correlation between the dermal fingerprintimage and the template is the greatest (when t corresponds to such anangle) where the template is rotated 360 degrees at the coordinates (x,y) of the dermal fingerprint image.

Also, at this time, the dermal ridge line direction (displacement angle)is expressed as a numerical value in the range up to 180 degrees in thecounterclockwise direction where the X axis positive direction is takenas 0 degree. However, since the 0 degree direction and the 180 degreesdirection need to be regarded as substantially the same direction, theinner product is yielded upon converting the angle of the directionvector so that the angle formed thereby with the X axis positivedirection (0 degree direction) is doubled.

The value of Ek (x, y) calculated by the Equation (1) above is an indexrepresenting the directional consistency between the dermal fingerprintimage and the template. Further, the comb type direction patterndetection unit 75 calculates a comb type evaluation value Wk (x, y)multiplied by the dermal ridge line intensity. The dermal ridge lineintensity represents dermal fingerprint likeness.

Wk(x,y)=max(0,Ek(x,y)−C)×Is(x,y)  [Equation 2]

In the above equation, C is an appropriately set threshold value. Thatis to say, the threshold value C has an effect of removing a portionwhere the value of Ek (x, y) is equal to or less than C as noise. Is (x,y) is an average value of the dermal ridge line intensity within thesame radius as the template where the coordinates (x, y) serves as thecenter.

That is to say, the evaluation value Wk (x, y) is obtained bysubtracting the threshold value C from the value of Ek (x, y) (in thecase where the result becomes negative, it is set to 0) and furthermultiplying by the dermal ridge line intensity in the vicinity of thecoordinate (x, y).

The comb type direction pattern detection unit 75 outputs thiscalculated value Wk (x, y) as a comb type abnormality degree (comb typeevaluation value). This comb type abnormality degree is a degreeindicating the likelihood of a comb type direction pattern.

The ω type direction pattern detection unit 76 preliminarily holds ωtype template data representing the direction pattern as shown in FIG.5B in the internal memory. The data structure of the ω type templatedata itself is similar to that of the comb type template data. The ωtype template data is template data representing a dermal ridge linedirection, and is preliminarily created based on an actual dermalfingerprint image having an ω type direction pattern. Based on the givendermal fingerprint image and the ω type template data above, the ω typedirection pattern detection unit 76 calculates an ω type abnormalitydegree Wo (x, y) by using the same procedure as that of the abovecalculation procedure of the comb type direction pattern detection unit75.

The X type direction pattern detection unit 77 preliminarily holds Xtype template data representing the direction pattern as shown in FIG.5A in the internal memory. The data structure of the X type templatedata itself is similar to that of the comb type template data. The Xtype template data is template data representing a dermal ridge linedirection, and is preliminarily created based on an actual dermalfingerprint image having an X type direction pattern. Based on the givendermal fingerprint image and the X type template data above, the X typedirection pattern detection unit 77 calculates an X type abnormalitydegree Wo (x, y) by using the same procedure as that of the abovecalculation procedure of the comb type direction pattern detection unit75.

The singular region detection unit 61 determines whether or not it is adermal fingerprint of an abnormal dermal ridge line direction based onwhether or not each maximum value of the comb type abnormality degree Wk(x, y) output from the comb type direction pattern detection unit 75,the ω type abnormality degree Wo (x, y) output from the ω type directionpattern detection unit 76, and the X type abnormality degree Wx (x, y)output from the X type direction pattern detection unit 77, exceeds apredetermined threshold. If the value exceeds the threshold value, thesingular region detection unit 61 determines that the dermal fingerprintimage is a dermal fingerprint of an abnormal dermal ridge line direction(that is to say, corresponds to a comb type direction pattern, an ω typedirection pattern, or an X type direction pattern). In other cases, thesingular region detection unit 61 determines that it is not a dermalfingerprint of an abnormal dermal ridge line direction.

As another method, the singular region detection unit 61 may determinewhether or not it is an abnormal dermal ridge line direction fingerprintbased on whether or not the sum of each maximum value of the comb typeabnormality degree Wk (x, y) output from the comb type direction patterndetection unit 75, the ω type abnormality degree Wo (x, y) output fromthe ω type direction pattern detection unit 76, and the X typeabnormality degree Wx (x, y) output from the X type direction patterndetection unit 77, exceeds a predetermined threshold. When the valueexceeds the threshold value, the singular region detection unit 61determines that the dermal fingerprint image is a dermal fingerprint ofan abnormal dermal ridge line direction. The singular region detectionunit 61 determines that it is not a dermal fingerprint of an abnormaldermal ridge line direction in other cases.

That is to say, the singular region detection unit 61 acquires dermalridge line direction information for each portion included in the dermalfingerprint image. Moreover, the singular region detection unit 61 findsan evaluation value indicating the extent to which the dermal ridge linedirection information has an abnormal dermal ridge line directionpattern, based on the correlation between the dermal ridge linedirection information, and the template of the abnormal dermal ridgeline direction pattern held preliminarily (such as the comb typedirection pattern, the ω type direction pattern, and the X typedirection pattern). Further, when the evaluation value is equal to orgreater than the predetermined threshold value, the singular regiondetection unit 61 detects a portion corresponding to the dermal ridgeline direction information as a singular region.

When it is determined that it is a dermal fingerprint of an abnormaldermal ridge line direction, the singular region detection unit 61outputs the information on the position of the singular region.

Weighting may be performed with a probability distribution of eachevaluation value (comb type abnormality degree, ω type abnormalitydegree, and X type abnormality degree) based on a database of actualdermal fingerprints. Thereby, the determination accuracy of the singularregion detection unit 61 can be further enhanced.

In the present exemplary embodiment, the singular region detection unit61 includes the comb type direction pattern detection unit 75, the ωtype direction pattern detection unit 76, and the X type directionpattern detection unit 77 in the interior thereof, and detects theabnormal dermal ridge line direction corresponding thereto. However, itis not limited to this type of configuration. The configuration may omitsome of these. Conversely, there may be provided templates of otherdirection patterns to detect abnormal dermal ridge line directions otherthan these three types. As an example, it is possible to adopt aconfiguration capable of detecting a pattern slightly changing thedermal ridge line angle of the comb type, the ω type, and the X type, ora configuration capable of detecting several types of patterns as aresult of changing the radius of the template.

The above method of detecting a singular region based on the number ofdirectional singular points and the positional relationship betweendirectional singular points, described as “(1) Abnormal PatternDetection”, is an effective technique when a clear image of an entiredermal fingerprint is obtained. On the other hand, in the present method((2) Abnormal Dermal Ridge Line Direction Detection) that usesevaluation values based on a template, there is an advantage that itenables detection of an abnormal dermal fingerprint of a specific shapeeven when only an image of only a fraction of the dermal fingerprint isacquired.

((3) Dermal Ridge Line Breakage Detection)

The singular region detection unit 61 also has a function of detectingbreakage of a dermal ridge line in the dermal fingerprint. Specifically,the singular region detection unit 61 includes a dermal ridge linebreakage detection unit 78.

The singular region detection unit 61 performs processing for detectingthese abnormal direction patterns by using information on the dermalridge line direction and information on the dermal ridge line intensityalready detected by the above method.

FIG. 6 is an example conceptually showing a dermal fingerprint imageincluding dermal ridge line breakage. In the example of the dermalfingerprint image shown in FIG. 7, a part of the dermal ridge lineswhich were originally continuous is discontinuous, and there is a dottedpattern in that part. In FIG. 7, a portion indicated by an ellipticalframe is a portion that includes dermal ridge line breakage. This typeof dermal ridge line breakage can be caused by burns that reach to thedermis, or damage due to chemicals reaching to the dermis.

The dermal ridge line breakage detection unit 78 acquires the data ofthe dermal ridge line direction image acquired by the above-describedmethod. This dermal ridge line direction image data includes dermalridge line direction data at each pixel. Then, the dermal ridge linebreakage detection unit 78 executes a direction smoothing process over alarge area. This direction smoothing process is a process of correctinga portion in the dermal fingerprint image including the dermal ridgeline direction detected in error due to noise or the like, to thecorrect dermal ridge line direction. The direction smoothing processingitself can be realized by statistical processing on pixel values ofdermal ridge line direction image data. The direction smoothing processis, for example, a process of taking a mode value of a directioncomponent of a region within a certain range, or an average of directionvectors of a region within a certain range.

FIG. 7 and FIG. 8 are schematic diagrams for illustrating examples ofthe direction smoothing processing mentioned above. FIG. 7 shows forexample dermal ridge line direction image data obtained for the examplefor the dermal fingerprint image in FIG. 6. In FIG. 6, the dermal ridgeline direction is indefinite with respect to the portion where thedermal ridge line is broken. The dermal ridge line direction image datafor this type of portion is susceptible to noise. This is because thedirection of the dermal ridge line to be detected is not stable.Therefore, in the central portion in FIG. 7, the dermal ridge linedirection is not constant but random. FIG. 8 is an image obtained as aresult of the direction smoothing process performed on the dermal ridgeline direction image in FIG. 7. By executing the direction smoothingprocess by means of the dermal ridge line breakage detection unit 78over a large area, it is possible to obtain the smoothly changingdirection image shown in FIG. 8.

Then, the dermal ridge line breakage detection unit 78 obtains anangular difference between the initial dermal ridge line direction andthe post-smoothing dermal ridge line direction, for each portion in thedirection image. When the angle (direction) has changed by apredetermined amount or more, that is, when the absolute value of theangular difference is equal to or greater than the predetermined amount,the dermal ridge line breakage detection unit 78 extracts this portionas a dermal ridge line breakage candidate region. With fingerprints ofthe epidermis, wrinkles and scars of elderly people or the like havethin linear shapes, and these can become ridge line breakage candidateregions. In contrast, the papillary layer is not affected by wrinkles.Moreover regarding scratches, normally these do not reach the dermis,and hence have no affect.

Then, the dermal ridge line breakage detection unit 78 finallycalculates the total sum of the dermal ridge line intensity alreadyobtained by the above-described processing for this dermal ridge linebreakage candidate region, thereby calculating and outputting anevaluation value for the dermal ridge line breakage detection. Then,when the evaluation value of the dermal ridge line breakage output bythe dermal ridge line breakage detection unit 78 is equal to or greaterthan a predetermined threshold value, the singular region detection unit61 determines the dermal fingerprint as having a dermal ridge linebreakage trace therein. In other cases, the singular region detectionunit 61 determines the dermal fingerprint as being a dermal fingerprinthaving no dermal ridge line breakage trace.

That is to say, the singular region detection unit 61 acquires dermalridge line direction information for each portion included in the dermalfingerprint image. In addition, the singular region detection unit 61obtains smoothed dermal ridge line direction information by performingdirection smoothing processing based on dermal ridge line directioninformation of a portion around each portion of the dermal ridge linedirection information. Furthermore, when (the absolute value of) thedifference between the dermal ridge line direction information and thesmoothed dermal ridge line direction information is greater than apredetermined threshold value, the singular region detection unit 61detects a region corresponding to that portion as the singular region.

When it is determined as being a dermal fingerprint having a dermalridge line breakage trace therein, the singular region detection unit 61outputs the information on the position of the singular region.

Among dermal ridge line breakages, there are not only the cases of burnsand chemicals, but also cases of dermal ridge line breakage due to yearsof aging deterioration and engaging in manual labor which abuses thehands. In the case of this type of natural breakage, not only a specificpart but also the entire dermal ridge line of the dermal fingerprint isbroken. In order to distinguish between this type of natural breakage ofthe entire dermal ridge line and partial breakage (including intentionalbreakage) due to burns and chemicals, the singular region detection unit61 may determine whether or not a portion of the dermal fingerprintother than the dermal ridge line breakage candidate region has ahigh-quality dermal ridge line image. As a result, it becomes possibleto detect only dermal ridge line breakage due to a specific condition.

The singular region detection unit 61 may also determine whether or nota dermal ridge line breakage trace is present in the central portion ofthe dermal fingerprint. Since the dermal fingerprint central portion hasa significant influence on the determination of the fingerprintcollation using the dermal fingerprint, dermal ridge line breakage maybe intentionally made in some cases. As a result, it also becomespossible to detect only dermal ridge line breakage in a specificlocation.

((4) Cutout Work Detection)

The singular region detection unit 61 also has a function of detectingcutout work processing of the dermal fingerprint. Specifically, thesingular region detection unit 61 includes a cutout work detection unit79. As will be described below, the cutout work detection unit 79determines the presence or absence of cutout work processing withrespect to the input dermal fingerprint image, based on the change inthe dermal ridge line pitch. This is because, in the case of a dermalfingerprint with cutout work having been surgically done thereto, sincethe skin around the surgical operation mark is pulled while beingsutured, the pitch of a specific portion of the dermal ridge line andthe pitch of the dermal ridge line in a specific direction locallychange.

FIG. 9 and FIG. 10 are schematic diagrams for explaining the cutout workprocessing of dermal fingerprints. FIG. 9 shows an example of a dermalfingerprint image before the cutout work is performed. Further, FIG. 10shows an example of a dermal fingerprint image after the cutout work hasbeen performed on the dermal fingerprint shown in FIG. 9. An example ofcutout work by surgery is a method such that a scalpel is placed in thediamond-shaped portion shown in the center of the dermal fingerprint inFIG. 9, the epidermis and dermis is cut out thereinside, and whilepulling the skin in the lateral direction, that is, in the left-rightdirection in a manner of closing the cut-out diamond shape, the centerpart of the original diamond shape is sutured.

In the case of performing a cutout work operation to achieve deformationon a dermal fingerprint shown in FIG. 10, the dermal ridge line, on theleft hand side of FIG. 10, in the direction orthogonal to the cutoutdirection (that is, the dermal ridge line running in the left-rightdirection in the present example. The portion indicated by “A” in FIG.10) does not receive any change as a result of pulling. On the otherhand, the dermal ridge line, on the right hand side of FIG. 10, in thedirection parallel to the cutout direction (that is, the dermal ridgerunning in the vertical direction in this example. The portion indicatedby “B” in FIG. 10) is observed with a characteristic in which the dermalridge line pitch spreads more than the original pitch.

A method of detection processing performed by the cutout work detectionunit 79 is as follows.

The cutout work detection unit 79 first detects the scar position onwhich the cutout work has been performed. Specifically, a line segmentof a certain length at an arbitrary angle from an arbitrary pixel in theimage is generated, and the dermal ridge line direction difference andthe dermal ridge line pitch difference are added for the image portionwithin a certain distance range (1 to 16 pixels) from line segments onboth sides of the line segment. The coordinates (x, y) and angle (t) atwhich the sum value is a maximum are taken as a candidate for the scarposition.

Next, the cutout work detection unit 79 calculates two types of cutoutwork evaluation values for rectangular regions (region R1 and region R2,respectively) of a predetermined size on both sides of the scar. Thefirst evaluation value Wc1 is an index for seeing whether or not thedermal ridge line pitch in the same direction as the scar is widening.The second evaluation value Wc2 is an index for seeing whether or notthe dermal ridge line pitches are different on both sides of the scar.The cutout work detection unit 79 calculates Wc1 and Wc2 by thefollowing equations.

$\begin{matrix}{{{wc}\; 1} = {\max\limits_{{R = {R\; 1}},{R\; 2}}\left\{ {\frac{\begin{pmatrix}{90 - {{Angle}\mspace{14mu} {difference}\mspace{14mu} {between}}} \\{\mspace{14mu} {{average}\mspace{14mu} {direction}\mspace{14mu} {within}\mspace{14mu} R\mspace{14mu} {and}\mspace{14mu} t}}\end{pmatrix}\mspace{31mu}}{90} \times {\max\left( {0,\frac{\begin{matrix}{{{Average}\mspace{14mu} {pitch}\mspace{14mu} {within}\mspace{14mu} R} -} \\{{Fingerprint}\mspace{14mu} {average}\mspace{14mu} {pitch}}\end{matrix}}{{Fingerprint}\mspace{14mu} {average}\mspace{14mu} {pitch}}} \right)} \times {Average}\mspace{14mu} {intensity}\mspace{14mu} {within}\mspace{14mu} R} \right\}}} & \left\lbrack {{Equation}\mspace{14mu} 3} \right\rbrack \\{{{wc}\; 2} = {\frac{\begin{matrix}{{{Average}\mspace{14mu} {pitch}\mspace{14mu} {within}\mspace{14mu} R\; 1} -} \\{{Average}\mspace{14mu} {pitch}\mspace{14mu} {within}\mspace{14mu} R\; 2}\end{matrix}}{{Fingerprint}\mspace{14mu} {average}\mspace{14mu} {pitch}} \times {\min \left( {{{Average}\mspace{14mu} {intensity}\mspace{14mu} {within}\mspace{14mu} R\; 1},{{Average}\mspace{14mu} {intensity}\mspace{14mu} {within}\mspace{14mu} R\; 2}} \right)}}} & \left\lbrack {{Equation}\mspace{14mu} 4} \right\rbrack\end{matrix}$

That is to say, for each of the regions R1 and R2, when a product of adegree to which the dermal ridge line direction in the region coincideswith “t”, a degree to which the dermal ridge line pitch in the region iswider than the dermal ridge line pitch of the entire dermal fingerprint(0 when it is narrower than the dermal ridge line pitch of the entiredermal fingerprint), and the dermal ridge line intensity in the regionis obtained, the greater value is the evaluation value Wc1.

Further, the evaluation value Wc2 is the product of the degree of thedifference between the dermal ridge line pitches in the regions R1 andR2 and the dermal ridge line intensity (the smaller one of the regionsR1 and R2).

The average direction in the above equation is calculated by taking aweighted average with respect to the direction data generated by thedermal ridge line direction detection unit 70 using weighting based onthe dermal ridge line intensity generated by the dermal ridge lineintensity detection unit 72. The average pitch in the above equation iscalculated by taking a weighted average with respect to the pitch datagenerated by the dermal ridge line pitch detection unit 71 usingweighting based on the dermal ridge line intensity generated by thedermal ridge line intensity detection unit 72.

The determination by means of the evaluation values Wc1 and Wc2calculated by the cutout work detection unit 79 is effective when thescar position is correctly detected. However, depending on the dermalfingerprints, there are some cases where the position of the cutout workis unclear and the scar position cannot be clearly known. In order tocope with these types of cases, a method of detecting whether or not anunnatural broad pitch portion exists in the entire dermal fingerprint isused concurrently, without using the scar position detected by thecutout work detection unit 79. Therefore, the following evaluationvalues Wc3 and Wc4 are used as indices. The evaluation value Wc3 is anindex for seeing whether or not an abnormal wide pitch portion exists.The evaluation value Wc4 is an index for seeing whether or not the pitchin a specific direction is widening. The cutout work detection unit 79calculates Wc3 and Wc4 by the following equations.

$\begin{matrix}{{{Wc}\; 3} = \frac{\begin{matrix}{{Total}\mspace{14mu} {sum}\mspace{14mu} {of}\mspace{14mu} {ridge}\mspace{14mu} {line}\mspace{14mu} {intensities}\mspace{14mu} {of}\mspace{14mu} 1.5\mspace{14mu} {or}} \\{{more}\mspace{14mu} {times}\mspace{14mu} {fingerprint}\mspace{14mu} {average}\mspace{14mu} {pitch}}\end{matrix}}{\begin{matrix}{{Total}\mspace{14mu} {sum}\mspace{14mu} {of}\mspace{14mu} {ridge}\mspace{14mu} {line}\mspace{14mu} {intensities}} \\{{of}\mspace{14mu} {entire}\mspace{14mu} {fingerprint}}\end{matrix}}} & \left\lbrack {{Equation}\mspace{14mu} 5} \right\rbrack \\{\mspace{79mu} {{{Wc}\; 4} = \frac{\begin{matrix}{{Average}\mspace{14mu} {pitch}\mspace{14mu} {of}\mspace{14mu} {direction}\mspace{14mu} {Dm} \times} \\{{average}\mspace{14mu} {intensity}\mspace{14mu} {of}\mspace{14mu} {direction}\mspace{14mu} {DM}}\end{matrix}}{{Average}\mspace{14mu} {pitch} \times {average}\mspace{14mu} {intensity}}}} & \left\lbrack {{Equation}\mspace{14mu} 6} \right\rbrack\end{matrix}$

In the equation of Wc4, Dm is a direction in which the average pitch isthe maximum.

That is to say, the evaluation value Wc3 represents the ratio of theportion of the entire dermal fingerprint where the dermal ridge linepitch is wide (based on the pitch 1.5 times the average of the entiredermal fingerprint), and is the value of the ratio with the dermal ridgeline intensities being taking into account.

The evaluation value Wc4 represents the ratio of the width of the pitchin the direction of a specific dermal ridge line (the direction in whichthe average pitch is the maximum) of the entire dermal fingerprint, andis the value of the ratio with the dermal ridge line intensities beingtaking into account. Magnification 1.5 is an example of the reference.

Finally, the cutout work detection unit 79 outputs the above-describedfour types of evaluation values Wc1, Wc2, Wc3, and Wc4. Then, thesingular region detection unit 61 determines whether or not cutout workis included in the dermal fingerprint image, depending on whether or notthe respective values of the evaluation values Wc1, Wc2, Wc3, and Wc4are equal to or greater than a predetermined threshold value. Inaddition, the singular region detection unit 61 multiplies each of theseevaluation values Wc1, Wc2, Wc3, and Wc4 by a predetermined weight toobtain a weighted average (weighted mean), and it is determined whetheror not cutout work is included in the dermal fingerprint image dependingon whether or not the weighted average is equal to or greater than thepredetermined threshold value.

That is to say, the singular region detection unit 61 acquires dermalridge line direction information as well as dermal ridge line pitchinformation for each portion included in the dermal fingerprint image.Moreover, the singular region detection unit 61 finds an evaluationvalue which takes a greater value as the difference in the dermal ridgeline direction and the difference in the dermal ridge line pitch becomegreater between adjacent regions in the dermal fingerprint image, basedon the dermal ridge line direction information and the dermal ridge linepitch information. Further, when the evaluation value is greater thanthe predetermined threshold value, the singular region detection unit 61detects that the adjacent region is a singular region due to cutoutwork.

When it is determined as being a dermal fingerprint with cutout workdone therein, the singular region detection unit 61 outputs theinformation on the position of the singular region.

Generally, in normal dermal fingerprints, it is known that the pitch ofthe dermal ridge line in the horizontal direction (short side directionof the finger) in the vicinity of the end of the lower part of thedermal fingerprint tends to be wider than the dermal ridge line pitch inthe other portions. Based on this, in the processing described above,the region in the lower part of the dermal fingerprint in which thedermal ridge line is in the horizontal direction may be excluded fromthe calculation of the evaluation values Wc1, Wc2, Wc3, and Wc4. Byperforming the calculation of the evaluation values by the cutout workdetection unit 79 in this manner, it is possible to further enhance thedetermination accuracy.

For example, in a situation such as a criminal investigation, in a casewhere a person from whom a fingerprint is to be collected does not wishto authenticate themselves, the fingerprint is impressed while beingintentionally twisted in some cases. Even in such a case, there is atendency for the specific region of the fingerprint and the pitch in thespecific direction to widen by pulling as a result of twisting.Similarly, it is considered that the dermal fingerprint also widens thespecific region and the pitch in the specific direction. The evaluationvalues Wc3 and Wc4 that do not use the scar position can also be usedfor the purpose of detecting a dermal fingerprint impressed in a stateunsuitable for authentication where an action such as twisting isapplied.

As described above, based on the image information of the papillarylayer acquired by the dermal image information acquisition unit 11, thesingular region detection unit 61 detects a singular region indicatingdamage of the papillary layer.

As a result, the singular region detection unit 61 can determine thepresence or absence of the singular region with high accuracy even whenthe state of the skin is not good, such as in the case where thefingerprint is unclear due to roughness, wrinkles due to aging and thelike, or burns. Thereby, the dermal image information processing device3 can reduce the possibility that the existence of the singular regionis missed and the same person is erroneously determined as a differentperson.

Further, the singular region detection unit 61 detects the directionalsingular point of the dermal ridge line included in the image of thepapillary layer, and detects the singular region based on the conditionof the number of each type of directional singular point or thecondition of the positional relationship between the types ofdirectional singular points.

As a result, the singular region detection unit 61 can detect a casewhere the number or the positional relationship is abnormal even if thepattern can exist in the dermal fingerprint image. In this respect, thesingular region detection unit 61 can detect an abnormality of thedermal fingerprint image with high accuracy.

Further, the singular region detection unit 61 acquires the dermal ridgeline direction information for each portion included in the image of thepapillary layer. At the same time, based on the correlation between thedermal ridge line direction information and the template of the abnormaldermal ridge line direction pattern held preliminarily, the singularregion detection unit 61 finds an evaluation value representing thedegree of abnormal dermal ridge line directional pattern possession inthe dermal ridge line direction information. When the evaluation valueis equal to or greater than a predetermined threshold value, thesingular region detection unit 61 detects a portion corresponding to thedermal ridge line direction information as a singular region.

As a result, the singular region detection unit 61 can detect with highaccuracy, a typical pattern in a singular region such as a dermal ridgeline direction which is likely to occur when the dermal fingerprint ischanged for example by surgery, by using a template. In particular, thesingular region detection unit 61 can detect an abnormal dermalfingerprint of a specific shape even when only a partial image of thedermal fingerprint is taken.

In addition, the singular region detection unit 61 acquires the dermalridge line direction information for each portion included in the imageof the papillary layer, and also acquires smoothed dermal ridge linedirection information that has been smoothed by direction smoothingprocessing based on dermal ridge line direction information of theportion around the relevant portion for each portion of the dermal ridgeline direction information. When the difference between the dermal ridgeline direction information and the smoothed dermal ridge line directioninformation is greater than a predetermined threshold value, thesingular region detection unit 61 detects the region corresponding tothat portion as a singular region.

As a result, the singular region detection unit 61 can detect thesingular region even for example when a ridge line of the dermis such asa burn reaching the dermis is not clear.

Further, the singular region detection unit 61 acquires dermal ridgeline direction information and dermal ridge line pitch information foreach portion included in the image of the papillary layer. At the sametime, the singular region detection unit 61 finds an evaluation valuewhich takes a greater value as the difference in the dermal ridge linedirection and the difference in the dermal ridge line pitch becomegreater between adjacent regions in the image of the papillary layer,based on the dermal ridge line direction information and the dermalridge line pitch information. Then, when the evaluation value is greaterthan the predetermined threshold value, the singular region detectionunit 61 detects that the adjacent region is a singular region due tocutout work.

As a result, the singular region detection unit 61 can detect thesingular region even when the scratch position is not clearly known.

In addition, the collation unit 116 performs a collation process on thedermal image information of the dermal image information acquired by thedermal image information acquisition unit 11 that is in a region otherthan the singular region detected by the singular region detection unit61, and the preliminary registration information being dermal imageinformation registered in advance in association with identifyinginformation for identifying the individual.

Thus, even when a singular region is included in the dermal image, thecollation unit 116 can prevent erroneously determining the same personas a different person due to the difference in the dermal fingerprint inthe singular region.

In addition, when performing the collation processing, the collationunit 116 makes at least either one of a positional deviation allowancewhich represents a degree to which positional deviation is allowed, anda mismatch allowance which represents a degree to which a mismatch isallowed, variable.

In particular, by increasing at least one of the positional deviationallowance and the mismatch allowance, the collation unit 116 can reducethe possibility of erroneously determining the same person as adifferent person.

In a fingerprint that is damaged due to a surgical operation or aninjury, the region except for the portion of the surgical operation orinjury maintains the characteristic amount of the original fingerprint.By verifying the consistency of this portion, there is a possibilitythat it can be collated with the fingerprint before the surgicaloperation or injury. Similarly for the dermal fingerprint, except forthe portion of the surgical operation or injury, there is a possibilitythat it can be collated with dermal fingerprints or fingerprints beforesurgery or injury.

On the other hand, in characteristic point collation, whether or not thesame fingerprint is present is determined by checking whether adjacentcharacteristic points (dermal ridge line end points and/or branchpoints) of the fingerprint are at a certain distance difference or acertain angular difference. In the case of surgically operatedfingerprints, in many cases, this allowance is exceeded by shape changedue to pulling at the time of suturing.

Therefore, for a fingerprint judged to be a damaged fingerprint, bymitigating the positional deviation allowance or mismatching allowanceof fingerprint characteristics at the time of collation from a standardvalue, it is possible to manufacture a device that is characterized bybeing capable of collating with the finger of the principal personbefore the damage was made thereto.

When mitigating collation allowance, there is a disadvantage that therisk of erroneously identifying a different person as the principalperson increases. However, in the operational environment in which anoperator or the like ultimately confirms whether he/she is the sameperson or not using a face photograph or the like other than thefingerprint, it is possible to reduce this type of risk ofmisidentifying another person.

With the above-described configuration, the dermal image informationprocessing device 3 can perform collation processing according to thepresence or absence of a singular region, based on the informationacquired by the singular region detection result acquisition unit 12. Inaddition, it is possible to perform collation processing according tothe position of the singular region.

Second Exemplary Embodiment

Next, a second exemplary embodiment will be described. Descriptions ofmatters common to those of the previously described exemplary embodimentmay be omitted, and the following description focuses on matters uniqueto the second exemplary embodiment.

FIG. 11 is a schematic block diagram showing a functional configurationof an image information processing system according to the secondexemplary embodiment. As shown in FIG. 11, an image informationprocessing system 4 includes an OCT 2, and a dermal image informationprocessing device 5. The dermal image information processing device 3includes a dermal image information acquisition unit 11, a singularregion detection result acquisition unit 12, a singular region detectionunit 61, a pre-registered information storage unit 62, a collation unit116, a result output unit 121, and a repair unit 214.

The singular region detection unit 61 and the pre-registered informationstorage unit 62 may be realized as functions of independent devices ormay be realized as functions of a part of other devices. Either one orboth of the singular region detection unit 61 and the pre-registeredinformation storage unit 62 may be realized as the internal function ofthe dermal image information processing device 3. The OCT 2 and thedermal image information processing device 3 may be integrallyconfigured. For example, the computer of the OCT 2 may execute thefunction of the dermal image information processing device 3.

Each of the dermal image information acquisition unit 11, the singularregion detection result acquisition unit 12, the collation unit 116, andthe result output unit 121 has the same function as each function in thefirst exemplary embodiment. The dermal image information processingdevice 5 according to the second exemplary embodiment includes a repairunit 214.

The repair unit 214 repairs the damage of the dermal image generated inthe singular region of the dermal image including the singular regionamong the dermal image information acquired by the dermal imageinformation acquisition unit 11.

The collation unit 116 in the second exemplary embodiment regards thedermal image information restored by the repair unit 214 as a regionother than the singular region, and performs collation processing.

Next, details of the process performed by the repair unit 214 will bedescribed. The repair unit 214 performs the process of repairing thedermal fingerprint of the singular region caused by a surgical operationcalled “Z type surgery”. The Z type surgery is a surgical operation inwhich a scalpel is inserted in a Z shape into the epidermis and dermis,and the skin (epidermis and dermis) of the two triangular portionscreated as a result of the Z-shaped incision is replaced and thensutured again. When such surgery is performed, a positional change ofthe characteristic amount of the dermal fingerprint occurs, so that itis difficult or impossible to collate as it is with the dermalfingerprint before the surgery.

FIG. 12 and FIG. 13 are schematic diagrams showing examples of dermalfingerprint images for explaining Z-type surgery. FIG. 12 shows an imagebefore performing the Z type surgery. FIG. 13 shows an image afterperforming the Z-type surgery. By replacing and suturing the twotriangular skins created as a result of the Z-shaped incision describedabove, the dermal fingerprint image shown in FIG. 13 has a pattern whichis not normally possible.

The dermal fingerprint image shown in FIG. 13 is an abnormal dermalfingerprint. The repair unit 214 repairs the dermal fingerprint imageshown in FIG. 13 created as a result of the Z type surgery, that is tosay, performs a process for processing the image, and performs a processfor restoring it to the original dermal fingerprint image (before thesurgery) in FIG. 12.

FIG. 14 is a block diagram showing a schematic functional configurationinside the repair unit 214. As shown in FIG. 14, the repair unit 214includes thereinside a damaged portion detection unit 91 and a Z typesurgery dermal fingerprint restoration unit 92.

Hereinafter, a method of processing performed by the repair unit 214will be described.

The damaged portion detection unit 91 detects a portion of the trace onwhich the operation has been performed from the dermal fingerprintimage, and outputs an abnormality degree image representing the degreeof abnormality as an image. As an example, in the abnormality degreeimage, the degree of abnormality is represented in grayscale in theimage.

As the degree of abnormality, the damaged portion detection unit 91 usesany one of a comb type evaluation value (comb type abnormality) Wk (x,y), an ω type evaluation value (ω type abnormality) Wo (x, y), and an Xtype evaluation value (X type abnormality) Wx (X, y) calculated by theaforementioned singular region detection unit 61. The damaged portiondetection unit 91 may receive these various evaluation values from thesingular region detection unit 61, or the damaged portion detection unit91 itself may calculate these various evaluation values by means of asimilar method. In addition, the damaged portion detection unit 91 mayuse another evaluation value (for example, a value indicating the degreeof direction change or pitch change as described above) as the degree ofabnormality. The damaged portion detection unit 91 may use a weightedaverage value obtained by weighting these various evaluation values andtaking the average as the abnormality degree. Then, the damaged portiondetection unit 91 creates an abnormality degree image using one of theabnormality degrees described here.

The Z type surgery dermal fingerprint restoration unit 92 receives inputof two images of a dermal fingerprint image and an abnormality levelimage created by the damaged portion detection unit 91, and outputs aprocessed dermal fingerprint restored image.

Specifically, first, the Z type surgery dermal fingerprint restorationunit 92 is a processing unit that performs a process of detecting alinear component from the abnormality degree image, and can beconfigured by applying Hough transformation to the abnormality degreeimage. As a result of this Hough transformation, the Z type surgerydermal fingerprint restoration unit 92 detects straight line componentsin the abnormality degree image. Then, the Z type surgery dermalfingerprint restoration unit 92 detects three straight line components(from the first candidate up to the third candidate) in which theportions with high abnormality degrees (dark portions in the case whereit is expressed as an abnormality degree grayscale image) are linearlyarranged. When these three straight line components from the firstcandidate to the third candidate form a “Z” shape on the dermalfingerprint, the Z type surgery dermal fingerprint restoration unit 92determines that the dermal fingerprint has undergone the Z shapeprocessing.

In order to determine whether or not the three straight line componentsfrom the first candidate to the third candidate form a “Z” shape, the Ztype surgery dermal fingerprint restoration unit 92 uses the followingconditions (1) to (3). The condition for determining a “Z” shape is thatall of the following conditions (1) to (3) are satisfied. A provision isthat in the condition (1) to the condition (3), the three straight linecomponents that are the first candidate to the third candidate arerepresented by straight lines (line segments) A, B, and C.

Condition (1): Two straight lines A and B the orientation (angle) ofwhich are closest to each other are near parallel. Specifically, thedifference between the orientations of the straight line A and thestraight line B is within 15 degrees, and also the straight lines A andB do not intersect within the image range. The above-mentioned 15degrees is an example of a value.

Condition (2): A straight line C other than A and B intersects each ofthe straight lines A and B in the image range at a difference oforientation (angle) of not less than 20 degrees and not more than 60degrees.

Condition (3): The average value of the pixel values of the abnormalitydegree images on the straight lines (line segments) A, B, and C is equalto or greater than a predetermined threshold value for each line segment(for all three lines).

FIG. 15 is a schematic diagram for explaining the method of restoring aZ type surgery dermal fingerprint. When it is determined that the inputdermal fingerprint image is a Z type surgery dermal fingerprint, the Ztype surgery dermal fingerprint restoration unit 92 restores thepreoperative image by the following method (Step (1) to Step (6)), andoutputs the obtained preoperative image. FIG. 15 shows three straightline component candidates (straight lines A, B, C) in the abnormal valueimage detected at the time of the above determination. Moreover, FIG. 15shows points D, E, F, and G used in the restoration procedure describedbelow.

Step (1): The point of intersection between the straight line A and thestraight line C is taken as D, and the intersection between the straightline C and the straight line B is taken as E.

Step (2): The foot of the perpendicular drawn from the intersectionpoint E onto the straight line A (the intersection between theperpendicular line and the straight line A) is taken as F.

Step (3): The foot of the perpendicular drawn from the intersectionpoint D onto the straight line B (the intersection between theperpendicular line and the straight line B) is taken as G.

Step (4): Copy the portion surrounded by the triangle FDE (firstpolygon) of the input image onto the triangle FGE of the output image bymeans of affine transformation.

Step (5): Copy the portion surrounded by the triangle DEG (secondpolygon) of the input image onto the triangle DFG of the output image bymeans of affine transformation.

Step (6): The regions other than the portions copied in the Steps (4)and (5) above are directly copied from the input image to the outputimage.

That is to say, based on the correlation between the dermal ridge linedirection information of each portion included in the dermal fingerprintimage and the template of the abnormal dermal ridge line directionpattern held preliminarily, the repair unit 214 finds an evaluationvalue representing the degree of abnormal dermal ridge line directionalpattern possession in the dermal ridge line direction information foreach of the portions, and extracts the straight line component of theevaluation value in the dermal fingerprint image. In addition, therepair unit 214 mutually replaces the dermal fingerprint images includedin the first polygon and the second polygon defined based on thesestraight line components (if the shape of the polygon to be replaceddiffers from the shape of the original polygon, the shape isappropriately adjusted by means of affine transformation or the like) tothereby repair the damage.

Although the points F and G used in the above method are not necessarilyguaranteed to be completely identical with the cutout part in the actualsurgical operation, the characteristic amounts of the dermal fingerprintimages on the two triangles FGE and DFG used in the above Steps (4) and(5) can be expected to approach the position of the dermal fingerprintbefore the surgical operation. That is to say, the repairing process ofthe repair unit 214 increases the possibility of successful collationwith the pre-registered information in the collation unit 116.

Further, in the case of handling a surgical dermal fingerprint(postoperative dermal fingerprint) with a portion that has been clearlyprocessed, by performing image matching (dermal ridge line matching) atthe boundary between the line segment DF and the line segment DE of thetransformed portion, the repair unit 214 may correct the coordinateposition of the point F which is the starting point F of the processing.Similarly, by performing image matching at the boundary between the linesegment EG and the line segment ED of the transformed portion, thecoordinate position of the point G serving as the starting point ofprocessing may be corrected.

Modified Example 1 of Repair Unit

The process of the repair unit 214 may be performed in a manner of thefollowing modified example.

Here is described a case where the input dermal fingerprint image isdetermined as containing cutout work damage, based on the evaluationvalues Wc1 and Wc2 calculated by the above-described cutout workdetection unit 79. In this case, the repair unit 214 detects arectangular region having a wide pitch on the wide pitch side of thedetected scar, calculates the product of the region width and the pitchchange difference in the rectangle, and estimates that it is the widthof the cutout portion. As a result, it is possible to restore theperipheral portion of the fingerprint outside the diamond shape byperforming image transformation such that the diamond region at thecenter part of FIG. 9 is inserted as a blank portion into the detectionrectangular region of the image in FIG. 10.

Modified Example 2 of Repair Unit

As a further modification of the repair unit 214, a repair unit 214 adescribed below may be used. The repair unit 214 a according to thepresent modified example does not restore the dermal fingerprint beforesurgery by means of transformation, but excludes the portion where thedermal fingerprint has been processed, extracts only the portion thathas not been processed, and outputs the extracted result as a restoredimage. That is to say, the repair unit 214 a cuts out a portion whichhas not been processed by means of surgery or the like.

FIG. 16 is a block diagram showing a schematic functional configurationof the repair unit 214 a according to present modified example. As shownin FIG. 17, the repair unit 214 a according to the present modifiedexample includes a damaged portion detection unit 93 and a damagedportion removal unit 94.

An example of the function of the damaged portion detection unit 93 issimilar to the function of the damaged portion detection unit 91described above. The damaged portion detection unit 93 may furtherinclude a function of detecting an abnormal wide pitch area or afunction of detecting a dermal ridge line damage region (a functionsimilar to the above-described dermal ridge line breakage detection unit78). As a result, it is possible to detect a damaged portion whiletaking the information of the abnormality degree image into account.

Based on the abnormality degree image generated by the damaged portiondetection unit 93, the damaged portion removal unit 94 decides anexclusion region to be excluded as a damaged portion by means of any ofthe methods listed below (method (1) to method (4)). Furthermore, thedamaged portion removal unit 94 fills the exclusion region in the dermalfingerprint image with a background color, and then outputs the image.

Method (1): A region whose degree of abnormality is equal to or greaterthan a predetermined threshold value and within 16 pixels in thevicinity thereof (this value “16” may be set to a different value) istaken as an exclusion region.

Method (2): Extracts a region where the degree of abnormality is equalto or greater than a predetermined threshold value, and treats theregion including the region inside the abnormal region as an exclusionregion by means of an image expansion and contraction process.

Method (3): A region where the degree of abnormality is equal to orgreater than a predetermined threshold is taken as an abnormal region,and a dermal fingerprint position that is furthest away from theabnormal region is detected. Also, a region within which the dermalridge line direction and the dermal ridge line pitch continuously varyfrom that position (no abnormal discontinuity) within a predetermineddistance is taken as an effective region. The portion other than theeffective region is taken as an exclusion region.

Method (4): A region where the degree of abnormality is equal to orgreater than a predetermined threshold is taken as an abnormal region,and a dermal fingerprint position that is furthest away from theabnormal region is detected. Also, the region outside the circle whichis a circle centered at that position and whose radius is the distancefrom that position to the abnormal region is taken as the exclusionregion.

That is to say, the repair unit 214 a repairs the damage by removing theinformation of the dermal fingerprint image of the exclusion regiondetermined based on the singular region, from the entire dermalfingerprint image. Here, the damaged portion is ignored or excluded fromthe evaluation, but the term “repair” is also used to include themeaning of correcting the verifiable image.

Whether to employ the method out of the above methods (1) to (4) can becontrolled for example by parameters given from the outside. As anothermethod, the method (4) is applied with the highest priority, and themethod (3) is applied when the region (area) of the dermal fingerprintimage necessary for the collation processing cannot be obtained as aresult thereof, and from thereon, the method (2) and the method (1) maybe applied in this order in a similar manner.

Although the processing by the Z type surgery dermal fingerprintrestoration unit 92 supports only damaged dermal fingerprints caused bysurgery of a specific method, if there is no clear surgical trace, thereis a possibility that the original preoperative dermal fingerprintcannot be restored. Even in such a case, there is an advantage that itcan still be collated with the dermal fingerprint of the principalperson before processing was done on the finger (alternatively, thefingerprint of the principal person before processing), by excluding theportion where the processing of the fingerprint has been performed, bymeans of the method using the damaged portion removal unit 94.

Also, the case of this modified example, in terms of removinginformation on the damaged portion, is an example of a case where therepair unit 214 a, concerning the dermal image information included in asingular region among the dermal image information acquired by thedermal information acquisition unit 11, repairs the damage in the dermalimage information that has occurred in this singular region.

The process performed by the repair unit 214 (or a modified examplethereof) (the process of restoring a Z type surgery dermal fingerprintto a state before surgical operation, or the process of excluding thedamaged portion) does not necessarily guarantee accurate restoration ofthe dermal fingerprint before the surgery. For example, a normal dermalfingerprint of a finger without a surgery history may be determined ashaving undergone a surgical operation as a result of a falsedetermination, and there may be some cases where it may still beprocessed. However, for example, by means of the collation unit 116checking both the dermal fingerprint image prior to the processing bythe repair unit 214 (or a modified example thereof) and the processeddermal fingerprint image against the pre-registered information storageunit 62 (fingerprint database), it is possible to reduce the risk oflowering the authentication rate. When collating both dermal fingerprintimages of before and after processing with the pre-registeredinformation storage unit 62, if one of the dermal fingerprint imagescoincides with a pre-registered dermal fingerprint image (or fingerprintimage), it can be regarded as matching with the pre-registered image.

Also, as a result of the processing performed by the repair unit 214 (ora modified example thereof), there is also a risk that the dermalfingerprint image after the restoration process coincides with thedermal fingerprint of another person. However, if the operation isperformed such that an operator or the like separately makes aconfirmation using means other than dermal fingerprints (for example, aface photograph, etc.) instead of making a final decision based only onthat match, this type of risk in misidentification of another person canbe reduced.

According to the configuration of the second exemplary embodiment, sincethe repair unit 214 (or its modification example) repairs the image ofthe papillary layer based on the information acquired by the singularregion detection result acquisition unit 12, the dermal imageinformation processing device 5 is able to perform collation processingusing the information after repair.

As described above, for the dermal image information included in thesingular region of the dermal image information acquired by the dermalimage information acquiring unit 11, the repair unit 214 repairs thedamage of the dermal image information in that singular region. Then,the collation unit 116 regards the dermal image information repaired bythe repair unit 214 as being in a region other than the singular regionand performs a collation processing.

In this way, by repairing the damage of the dermal image information bythe repair unit 214, it is possible to improve the accuracy of thecollation processing performed by the collation unit 116.

Furthermore, the repair unit 214 excludes the exclusion region definedbased on the singular region, from the image of the papillary layer, tothereby repair the damage.

Thus, even when the dermal fingerprint before surgery can not berestored, such as in the case where a clear surgical trace is not seen,the repair unit 214 can perform collation by excluding the part wherethe dermal fingerprint has been deformed by surgery. As a result, theaccuracy of the collation processing performed by the collation unit 116can be improved.

Moreover, based on the correlation between the dermal ridge linedirection information of each portion included in the image of thepapillary layer, and the template of the abnormal dermal ridge linedirection pattern held preliminarily, the repair unit 214 finds anevaluation value representing the degree of abnormal dermal ridge linedirectional pattern possession in the dermal ridge line directioninformation for each of the portions, and extracts the straight linecomponent of the evaluation value in the image of the papillary layer.In addition, the repair unit 214 mutually replaces the image of thepapillary layer included in the first polygon and the second polygondefined based on these straight line components to thereby repair thedamage.

As a result, the repair unit 214 can restore the dermal fingerprintimage before surgery, from the dermal fingerprint image in which thedermis is partially replaced by surgery, such as a dermal fingerprintimage of Z type surgery.

Next, the configuration of a third exemplary embodiment of the presentinvention will be described with reference to FIG. 17.

FIG. 17 is a schematic block diagram showing a configuration of a dermalimage information processing device according to the third exemplaryembodiment of the present invention. The dermal image informationprocessing device 301 shown in FIG. 17 includes a dermal imageinformation acquisition unit 302, and a singular region detection unit303.

With such a configuration, the dermal image information acquisition unit302 acquires image information of the papillary layer. Moreover, thesingular region detection unit 303 detects a singular region indicatingdamage of the papilla layer, based on the image information of thepapilla layer acquired by the dermal image information acquisition unit302.

As a result, the singular region detection unit 303 can determine thepresence or absence of the singular region with high accuracy even whenthe state of the skin is not good, such as in the case where thefingerprint is unclear due to roughness, wrinkles due to aging and thelike, or burns. Thereby, the dermal image information processing device301 can reduce the possibility that the existence of the singular regionis missed and the same person is erroneously determined as a differentperson.

A program for realizing all or a part of the functions of the dermalimage information processing device 3 or 5 may be recorded on acomputer-readable recording medium, and the program recorded on therecording medium may be read and executed to thereby perform theprocessing of each unit. The term “computer system” referred to hereincludes hardware such as an OS and peripheral devices.

The term “computer-readable recording medium” refers to a portablemedium such as a flexible disk, a magnetic optical disk, a ROM, and aCD-ROM, or a memory device such as a hard disk built in a computersystem. Furthermore, the “computer-readable recording medium” mayinclude one that dynamically holds a program for a short time, such as acommunication line for transmitting a program via a network such as theInternet or a communication line such as a telephone line, and one thatholds a program for a certain period of time such as a volatile memoryinside a computer system serving as a server or a client in that case.Further, the program above may be for realizing a part of theabove-described functions, or may be one which can realize theabove-mentioned functions in combination with a program already recordedin the computer system.

The exemplary embodiments of the present invention have been describedabove in detail with reference to the figures. However, the specificconfiguration is not limited to these exemplary embodiments, and designsand the like without deviating from the scope of the present inventionare included.

INDUSTRIAL APPLICABILITY

The present invention may be applied to a dermal image informationprocessing device, a dermal image information processing method, and aprogram.

REFERENCE SYMBOLS

-   1, 4 Dermal image information processing system-   2 OCT-   3, 5, 301 Dermal image information processing device-   11, 302 Dermal image information acquisition unit-   12 Singular region detection result acquisition unit-   61, 303 Singular region detection unit-   62 Pre-registered information storage unit-   70 Dermal ridge line direction detection unit-   71 Dermal ridge line pitch detection unit-   72 Dermal ridge line intensity detection unit-   73 Directional singular point detection unit-   74 Abnormal pattern detection unit-   75 Comb type direction pattern detection unit-   76 ω type direction pattern detection unit-   77 X type direction pattern detection unit-   78 Dermal ridge line breakage detection unit-   79 Cutout work detection unit-   91, 93 Damaged portion detection unit-   92 Z type surgery dermal fingerprint restoration unit-   94 Damaged portion removal unit-   116 Collation unit-   121 Result output unit-   214, 214 a Repair unit

1. A dermal image information processing device comprising: a memory;and a hardware component that reads data from the memory and isconfigured to: acquire dermal image information showing ridge lines in apapillary layer; detect an singular region in a pattern of the ridgelines; detect a position that is furthest away from the singular region;determine a region for collation based on the detected position; andperform collation of the pattern of the ridge lines using only featurepoints that are included in the region for collation.
 2. The dermalimage information processing device according to claim 1, wherein thehardware component is configured to determine, as the region forcollation, a region within which transition of directions of the ridgelines from the detected position and pitches of the ridge lines from thedetected position are not abnormal.
 3. The dermal image informationprocessing device according to claim 1, wherein the hardware componentis configured to determine, as the region for collation, a region ofpoints included a circle whose radius is equal to a length between thedetected position and the abnormal region, the circle being centered atthe detected position.
 4. The dermal image information processing deviceaccording to claim 1, wherein the hardware component is furtherconfigured to: when performing collation of the pattern of the ridgelines in which the singular region is detected with a pre-registeredpattern, change at least either one of a positional deviation allowancewhich represents a degree to which positional deviation is allowed, anda mismatch allowance which represents a degree to which a mismatch isallowed, such that the pattern of the ridge lines in which the singularregion is detected become more likely to be regarded to be same as thepre-registered pattern.
 5. A dermal image processing method comprising:acquiring dermal image information showing ridge lines in a papillarylayer; detecting an singular region in a pattern of the ridge lines;detecting a position that is furthest away from the singular region;determining a region for collation based on the detected position; andperforming collation of the pattern of the ridge lines using onlyfeature points that are included in the region for collation.
 6. Thedermal image information processing method according to claim 5,comprising determining, as the region for collation, a region withinwhich transition of directions of the ridge lines from the detectedposition and pitches of the ridge lines from the detected position arenot abnormal.
 7. The dermal image information processing methodaccording to claim 5, comprising determining, as the region forcollation, a region of points included a circle whose radius is equal toa length between the detected position and the abnormal region, thecircle being centered at the detected position.
 8. The dermal imageinformation processing method according to claim 5, further comprisingchanging, when performing collation of the pattern of the ridge lines inwhich the singular region is detected with a pre-registered pattern, atleast either one of a positional deviation allowance which represents adegree to which positional deviation is allowed, and a mismatchallowance which represents a degree to which a mismatch is allowed, suchthat the pattern of the ridge lines in which the singular region isdetected become more likely to be regarded to be same as thepre-registered pattern.
 9. A non-transitory computer-readable storagemedium storing a program that causes a computer to perform: acquiringdermal image information showing ridge lines in a papillary layer;detecting an singular region in a pattern of the ridge lines; detectinga position that is furthest away from the singular region; determining aregion for collation based on the detected position; and performingcollation of the pattern of the ridge lines using only feature pointsthat are included in the region for collation.
 10. The storage mediumaccording to claim 9, wherein the program further causes the computer toperform determining, as the region for collation, a region within whichtransition of directions of the ridge lines from the detected positionand pitches of the ridge lines from the detected position are notabnormal.
 11. The storage medium according to claim 9, wherein theprogram further causes the computer to perform determining, as theregion for collation, a region of points included a circle whose radiusis equal to a length between the detected position and the abnormalregion, the circle being centered at the detected position.
 12. Thestorage medium according to claim 9, wherein the program further causesthe computer to perform changing, when performing collation of thepattern of the ridge lines in which the singular region is detected witha pre-registered pattern, at least either one of a positional deviationallowance which represents a degree to which positional deviation isallowed, and a mismatch allowance which represents a degree to which amismatch is allowed, such that the pattern of the ridge lines in whichthe singular region is detected become more likely to be regarded to besame as the pre-registered pattern.